I wouldn't know why your bank isn't listed here, but what I do know is;
...As long as your phone number is the same number you get your bank alert sms' on, then you're free to dial the corresponding code to BUY airtime anytime and at your comfort from your bank.
Give it a try, it works, its been working, and for some banks it's been working for close to a year now.
(This Works On All Mobile Phones)
#Enjoy
1.Access bank: *901* amount#
2.Eco bank*326*amount#
3.Fidelity: *770*amount#
4.FCMB: *389*214*amount#
5.First Bank: *894*amount#
6.GTB *737*amount#
7.heritage Bank *322*030*amount#
8.keystone *322*082*amount#
9.Skye Bank *389*076*1*amount#
10.IBTC: *909*amount#
11.Sterling *822*amount#
12.UBA: *389*033*1*amount#
13.Unity Bank: *322*215*amount#
14. Zenith Bank *302*amount#
15. Stanbic IBTC *909*amount#
For banks not listed, please contact customer service nos behind your ATM card for more information.
It's The Wordsmith™